Results 31 to 40 of about 22,331 (301)

STUDY OF SYMMETRY IN F(R) THEORY OF GRAVITY [PDF]

Modern Physics Letters A, 2010
An action in which the Ricci scalar is non-minimally coupled with a scalar field and contains higher order curvature invariant terms carries a conserved current under certain conditions that decouples geometric part from the scalar field. The conserved current relates the pair of arbitrary coupling parameters f(ϕ) and ω(ϕ) with the gravitational field
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Pre-inflationary bounce effects on primordial gravitational waves of f(R) gravity

Physics Letters B, 2022
In this work we shall study a possible pre-inflationary scenario for our Universe and how this might be realized by f(R) gravity. Specifically, we shall introduce a scenario in which the Universe in the pre-inflationary era contracts until it reaches a ...
S.D. Odintsov, V.K. Oikonomou
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EMERGENT UNIVERSE IN THE CHAMELEON, f(R) AND f(T) GRAVITY THEORIES [PDF]

International Journal of Modern Physics D, 2011
In this work, we consider an emergent Universe in generalized gravity theories like the chameleon, f(R) and f(T) gravities. We reconstruct the potential of the chameleon field under the emergent scenario of the Universe and observe its increasing nature with the evolution of the Universe.
Chattopadhyay, Surajit, Debnath, Ujjal
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Massive white dwarfs in $$f(\mathtt {R,L_m})$$ f ( R , L m ) gravity

European Physical Journal C: Particles and Fields, 2022
In this work, we investigate the equilibrium configurations of massive white dwarfs (MWD) in the context of modified gravity, namely $$f(\mathtt {R,L_m})$$ f ( R , L m ) gravity, where $$\mathtt {R}$$ R stands for the Ricci scalar and $$\mathtt {L_m}$$ L
R. V. Lobato, G. A. Carvalho, N. G. Kelkar, M. Nowakowski   +3 more
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A study of cylindrically symmetric solutions in $$f(R, \phi , X)$$ f ( R , ϕ , X ) theory of gravity

European Physical Journal C: Particles and Fields, 2022
In this article, we aim to investigate some cylindrically symmetric solutions in a very well known modified theory named as $$f(R, \phi , X)$$ f ( R , ϕ , X ) theory of gravity, where the terms R, $$\phi $$ ϕ and X are clarified as Ricci Scalar, scalar ...
Adnan Malik, Ayesha Nafees, Akram Ali, Muhammad Naeem Butt   +3 more
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Charged wormholes in f(R,T)-extended theory of gravity [PDF]

International Journal of Modern Physics D, 2019
Wormholes (WHs) are a solution for General Relativity field equations which characterize a passage or tunnel that connects two different regions of spacetime and is filled by some sort of exotic matter that does not satisfy the energy conditions. On the other hand, it is known that in extended theories of gravity, the extra degrees of freedom once ...
P. H. R. S. Moraes, W. de Paula, R. A. C. Correa   +2 more
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ENERGY CONDITIONS IN f(R) GRAVITY AND BRANS–DICKE THEORIES [PDF]

International Journal of Modern Physics D, 2009
The equivalence between f(R) gravity and scalar–tensor theories is invoked to study the null, strong, weak and dominant energy conditions in Brans–Dicke theory. We consider the validity of the energy conditions in Brans–Dicke theory by invoking the energy conditions derived from a generic f(R) theory. The parameters involved are shown to be consistent
Atazadeh, K., Khaleghi, A., Sepangi, H. R., Tavakoli, Y.   +3 more
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Neutron stars in $$f(\mathtt {R,L_m})$$ f ( R , L m ) gravity with realistic equations of state: joint-constrains with GW170817, massive pulsars, and the PSR J0030+0451 mass-radius from NICER data

European Physical Journal C: Particles and Fields, 2021
In this work, we investigate neutron stars (NS) in $$f(\mathtt {R,L_m})$$ f ( R , L m ) theory of gravity for the case $$f(\mathtt {R,L_m})= \mathtt {R}+ \mathtt {L_m}+ \sigma \mathtt {R}\mathtt {L_m}$$ f ( R , L m ) = R + L m + σ R L m , where $$\mathtt
R. V. Lobato, G. A. Carvalho, C. A. Bertulani   +2 more
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New classes of modified teleparallel gravity models

Physics Letters B, 2017
New classes of modified teleparallel theories of gravity are introduced. The action of this theory is constructed to be a function of the irreducible parts of torsion f(Tax,Tten,Tvec), where Tax,Tten and Tvec are squares of the axial, tensor and vector ...
Sebastian Bahamonde, Christian G. Böhmer, Martin Krššák   +2 more
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Redundant operators in the exact renormalisation group and in the f(R) approximation to asymptotic safety

, 2013
In this paper we review the definition and properties of redundant operators in the exact renormalisation group. We explain why it is important to require them to be eigenoperators and why generically they appear only as a consequence of symmetries of ...
Morris, Tim R., Dietz, Juergen A.
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